If there's one thing former Alaska Gov. Sarah Palin and President Obama have in common, it may just be a belief in the importance of prayer and the federal government's role in setting aside a day for it.

Today is the National Day of Prayer, required by law since 1952, when the president calls on Americans to "turn to God in prayer and meditation."

From conference rooms in government office buildings to private chapels, the steps of the U.S. Capitol and thePentagon, thousands will gather across the country to express publicly their faith in the federally-sanctioned tradition.

But this year's observance comes as the 59-year-old practice is under fire and facing a possible ban after a federal district court last month ruled that the prayer day violates the First Amendment's Establishment Clause, which prohibits the government from imposing an official religion or showing preference to one.

The National Day of Prayer "serves no purpose but to encourage a religious exercise, making it difficult for a reasonable observer to see the statute as anything other than a religious endorsement," Judge Barbara Crabb of the U.S. District Court for the Western District ofWisconsin wrote April 15.

"No one can doubt the important role that prayer plays in the spiritual life of a believer. … However, [that doesn't mean] the government may enact a statute in support of it, any more than the government may encourage citizens to fast during the month of Ramadan, attend a synagogue, purify themselves in a sweat lodge or practice rune magic," Crabb wrote.

Enforcement of the ruling is on hold while an appeals court hears the case. The Obama administration, the respondent in the case, contends that the day is only an "acknowledgement" of the country's religious tradition.

"Prayer has been a sustaining way for many Americans of diverse faiths to express their most cherished beliefs, and thus we have long deemed it fitting and proper to publicly recognize the importance of prayer on this day," Obama wrote in his official proclamation.

The case, brought by the Freedom from Religion Foundation, a group of atheists and agnostics, now puts the administration in an uncomfortable position of defending something against the wishes of a constituency that it has tried to court as part of its commitment to pluralism and diversity.

"It is such a profound violation of conscience for Congress to direct our president to tell all citizens to pray, and that they in fact must set aside an entire day for prayer once a year," foundation president Annie Laurie Gaylor said.